Investigations on multi-slope energy decay formation within single-space monumental structures by diffusion equation modeling and intensity probe measurements

Abstract

Multiple domed superstructures with different volumetric and material attributes are previously investigated using in-situ acoustical measurements and acoustical simulation methods for analyzing their contributions to multi-slope energy decay formation. Relevant acoustical parameters including decay rates and decay times are computed by applying the Bayesian decay analysis. Initial results indicate double- or triple-slope decay characteristics for specific measurement configurations for selected cases. The ongoing research is aimed at explaining the probable reasons of multiple decay formation as observed in such single space enclosures. Diffusion equation modeling (DEM) and intensity probe measurements are utilized to observe spatial sound energy distributions and energy flow vectors. Both computed and measured flow vectors indicate the contribution of central dome to the later energy feedback. For a specific case the trial by DEM over virtual model with floor with marble instead of carpet resulted in a centrally concentrated energy, as a result preventing the multi-slope formation. The results support the argument that non-diffuse sound fields due to geometrical and material characteristics of superstructures provide the circumstances for non-exponential energy decay formation.